I've been experimenting with using circuits to set recipes. This latest one was a lot of fun because it has to make water to feed back into itself for the other two recipes. The circuit logic is surprisingly simple with the new selector combinator and combinators being able to use red and green wire signals separately
The core is a constant combinator with levels I want outputting on the red line, an arithmetic combinator which takes in green for gathered amount and red for requested amount. This core can be used for anything where I want to know how short I am on something. For the fuel specifically I can just use a selector combinator to see what is most in need and make that, and set water to be higher than the other two so I don't accidentally run out of both water and something else and have it try and make the other thing with no available water. For other systems, such as an omni-assembler that's trying to make belts and gears, the logic to choose what to build isn't quite as simple.